First, I would like to state that I understand DPI and how it relates to print image resolution (400x600px = 4x6inch @ 100dpi, 800x1200px = 4x6inch @ 200dpi... etc).
What I would like to know is what is the significance of the DPI stated on the file properties or EXIF information (listed as Horizontal & Vertical Resolution) of an image?
I have had several makes and models of digital cameras, it seems this information is brand specific, I have had two Olympus Digital Cameras, one a 3MP & one 5MP, both always listed this number as 72dpi.
On Canon digital cameras (I had a 4MP), this number appears as 180dpi, and on Nikon digital cameras (4MP & 5MP), it is 300dpi. The number never changes based on quality/size settings.
I think this number is one of the areas of confusion when people speak about DPI, because when you view your file info, and see it says "300dpi" a person may think that an image is 300dpi print quality regardless of the pixel dimension. Is it just what the camera manufacturer programs in, or does it relate to the sensor in the camera, I would like to understand what this number means, if anything?
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